For example, a reinforcement part (door reinforcement) of a vehicular door is formed by roll forming a zinc-plated steel strip, cutting the steel strip into a predetermined length and then heat treating the same so as to secure desired strength.
Therefore, the reinforcement part of the vehicular door is manufactured through the roll forming process and the heat treatment process thereafter.
JP-A-2007-83304 discloses a forming apparatus that bends and forms a roll-formed product after roll-forming of a metallic steel plate. According to the forming apparatus disclosed in JP-A-2007-83304, the roll-formed product is bent and heated at the same time and is then rapidly cooled, so that the heat-treated roll-formed product is manufactured.